Engineering Commons^™

Quantifying Individual Losses In A Direct Methanol Fuel Cell, Jennifer Rae Ruffing

Theses and Dissertations

The performance of a direct methanol fuel cell (DMFC) is complicated due to the complex interactions of kinetic and transport processes. As a result, changes in one aspect of the cell have consequences in other aspects, which are difficult to elucidate from the full-cell polarization (i.e. voltage vs. current) behavior that fuel cell researchers often use to characterize the performance of their systems. The objective of this work was to develop a strategy to use current and voltage relationships from anode half cells, cathode half-cells, and a hydrogen pump, coupled with methanol crossover data and a mathematical model, to quantify …

Theoretical Investigation Of The Water-Gas Shift Reaction At The Three Phase Boundary Of Ceria Supported Platinum Metal Clusters, Sara Aranifard

Theses and Dissertations

The Water-Gas Shift (WGS: CO+H2O→CO2+H2) reaction is a key step in hydrogen fuel processing for mobile fuel cell applications. Since the reaction is equilibrium-limited and exothermic, high conversions are favored by low temperatures. However, conventional low-temperature shift catalysts are not active enough. Reducible oxide supported small noble metal clusters have shown excellent activity as low temperature WGS catalysts and it is generally believed that these catalysts are bifunctional. In other words, the reaction occurs at the three-phase boundary (TPB) of the noble metal, the reducible oxide, and the gas phase. The small noble metal cluster adsorbs/activates the CO molecules and …

Enantioselective Hydrogenation Of Α-Methylcinnamic Acid Over Pd/Al2o3: A Spectroscopic And Kinetic Study, Xiaojing Sun

Theses and Dissertations

Hydrogenation of C=C in α-methylcinnamic acid (MCA) is studied by both kinetic and spectroscopic method. Kinetic study was in a semi-batch reactor. The reaction activity is strongly solvent dependent, while selectivity remains almost unaffected. The reaction is zero order in hydrogen pressure and first order in MCA. The presence of cinchonidine does not affect the reaction order with respect to either acid or H2 pressure, but has a significant inhibiting effect on the reaction rate. The catalyst exhibits stable activity during the reaction with no sign of deactivation. The adsorption and hydrogenation in dichloromethane, isopropanol and 1, 4-Dioxane over the …

Asymmetric Hydrogenation Of Α, Β-Unsaturated Carboxylic Acid Over Chiral-Modified Palladium Catalyst, Shuai Tan

Theses and Dissertations

The production of optically pure chemicals through enantioselective catalytic reaction plays a key role a variety of industrials (e.g., pharmaceutical, agrochemical). Among several established methods, chiral-modified supported transition metal catalyst has been addressed attentions since past decades due to an environmental concern. Asymmetric hydrogenation of α, β-unsaturated carboxylic acid over Pd catalyst is of particular interest in this area. Nevertheless, the spectroscopic aspect, as well as the kinetic mechanism of such reaction system are still not clearly understood and require further study. In this work, a model catalytic reaction has been investigated from both spectroscopic and kinetic view. To be …

Effect Of Matrix Modulus On Cancer Stem Cells And Tumorsphere Formation In Three-Dimensional-Engineered Matrix, Samaneh Kamali Sarvestani

Theses and Dissertations

Maintenance of cancer stem cells (CSCs) is regulated by their microenvironment. As cancer cells are affected by many factors in their microenvironment, a major challenge is to isolate the effect of a specific factor on cancer stem cells (CSCs) while keeping other factors unchanged. We have developed a synthetic inert 3D polyethylene glycol diacrylate (PEGDA) gel culture system as a unique tool to study the effect of microenvironmental factors on CSCs response. Synthetic hydrogels provide the flexibility to design three-dimensional (3D) matrices to isolate and study individual factors in the tumor microenvironment.

The objective of this work was to investigate …